This invention is a computer device to aid a spot bowler choose a starting position and a direction to roll the second ball in a frame to achieve a spare. The terms, "strike", "spare", "frame" are widely-used bowling parlance and need no further explanation to practitioners of the sport of bowling to whom this invention is of interest.
There have been several patents issued for inventions for aiding a bowler improve his or her game. Because of the nature of the objective of these inventions, they all contain common features such as a representation of a bowling lane and a means of assisting a bowler choose a starting position and a direction to roll the ball so that the required group of bowling pins will be knocked down to achieve a spare. Several of the inventions, for example, Pomranz in U.S. Pat. No. 2,942,358, Peterson in U.S. Pat. No. 3,012,339, Tomblin in U.S. Pat. No. 3,279,097, or Burger in U.S. Pat. No. 4,035,931 teach the use of means that require the user to represent the path of a bowled ball in some detail. Other inventions, such as Marting in U.S. Pat. No. 3,989,810 teach means that are complicated in structure. Still other inventions, such as Dell in U.S. Pat. No. 2,934,837, teach the use of means that may be accurate only if the ball is bowled with a path that has only slight curvature.
The present invention is readily and inexpensively fabricated and is very easy to use. From the trajectory of a bowled ball that achieves a strike, a straight line is traced on a transparent member that has a bowling ball indicator in the pin deck area. This calibrates the device. The relative position of the transparent member and a member that has a representation of a bowling lane are adjusted so that the bowling ball indicator has the proper approach to a bowling pin sought to be struck. The position of the calibration line will then indicate the starting position and the spot on the array of targets at which to aim.